This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered drum, or flexible, belt imaging members, or devices comprised of a first layer, a supporting medium like a substrate, a photogenerating layer, and a charge transport layer, including a plurality of charge transport layers, such as a first charge transport layer and a second charge transport layer, an optional adhesive layer, an optional hole blocking or undercoat layer, and an optional overcoat layer, and wherein the supporting substrate is situated between the first layer and the photogenerating layer. More specifically, the photoconductors disclosed contain a first anticurl backside coating layer or curl deterring backside coating layer (ACBC) to, for example, render imaging member flatness, and other advantages as illustrated herein, and which layer is in contact with and contiguous to the reverse side of the supporting substrate, that is the side of the substrate that is not in contact with the photogenerating layer, and which first layer, the ACBC layer of the present disclosure, is comprised of a fluorinated, especially a soluble, in for example, an alkylene halide, like methylene chloride, fluorinated poly(oxetane) polymer.
With the soluble fluorinated poly(oxetane) polymer, the ACBC layer possesses a desirable low surface energy, thus the wear resistance of this layer is excellent especially as compared to an ACBC layer without any fluorinated polymer or an ACBC layer containing polytetrafluoroethylene (PTFE). Moreover, the ACBC layer of the present disclosure contains an environmentally suitable non-hazardous soluble fluorinated polymer as compared, for example, to PTFE; the coating solution containing the fluorinated poly(oxetane) polymer is stable for extended time periods, and avoids the use of the undesirable perfluorooctane acid (PFOA) in the preparation of the fluorinated poly(oxetane) polymer; minimal agglomeration of the ACBC layer components thereby increasing the slipperiness of this layer; in place of the micron-sized particles of PTFE, the use of molecularly dispersed (soluble) or microphase-separated (nano-sized domains) additives of fluorinated poly(oxetane) polymer substantially avoid the escape of the polymer particles when the ACBC layer is abraded or worn thus adversely impacting the systems in which the ACBC layer is present; and other advantages as illustrated herein for photoconductors with ACBC layers comprising a fluorinated poly(oxetane) polymer.
Also, in embodiments of the present disclosure there are provided photoconductors containing a fluorinated poly(oxetane) polymer in at least one of the ACBC layer, and an overcoat layer.
In some instances when a flexible layered photoconductor belt is mounted over a belt support module comprising various supporting rollers and backer bars in a xerographic imaging apparatus, the anticurl or reduction in curl backside coating (ACBC), functioning under a normal xerographic machine operation condition, is repeatedly subjected to mechanical sliding contact against the apparatus backer bars and the belt support module rollers to thereby adversely impact the ACBC wear characteristics. Moreover, with a number of known prior art ACBC photoconductor layers formulated to contain non-needle like additives the mechanical interactions against the belt support module components can decrease the lifetime of the photoconductor primarily because of wear and degradation after short time periods.
In embodiments, the photoconductors disclosed include an ACBC (anticurl backside coating) layer on the reverse side of the supporting substrate of a belt photoreceptor. The ACBC layer, which can be solution coated, for example, as a self-adhesive layer on the reverse side of the substrate of the photoreceptor, may comprise a number of suitable fluorinated poly(oxetane) materials such as those components that substantially reduce surface contact friction and prevent or minimize wear/scratch problems for the photoreceptor device. In embodiments, the mechanically robust ACBC layer of the present disclosure usually will not substantially reduce the layer's thickness over extended time periods to adversely affect its anticurl ability for maintaining effective imaging member belt flatness, for example when not flat, the ACBC layer can cause undesirable upward belt curling which adversely impacts imaging member belt surface charging uniformity causing print defects which thereby prevent the imaging process from continuously allowing a satisfactory copy printout quality; moreover, ACBC wear also produces dirt and debris resulting in dusty machine operation condition. Since the ACBC layer is located on the reverse side of the photoconductor, it does not usually adversely interfere with the xerographic performance of the photoconductor, and decouples the mechanical performance from the electrical performance of the photoconductor.
Moreover, high surface contact friction of the anticurl backside coating against the machine, such as printers, subsystems can cause the development of undesirable electrostatic charge buildup. In a number of instances with devices, such as printers, the electrostatic charge builds up because of high contact friction between the anticurl backside coating and the backer bars which increases the frictional force to the point that it requires higher torque from the driving motor to pull the belt for effective cycling motion. In a full color electrophotographic apparatus, using a 10-pitch photoreceptor belt, this electrostatic charge build-up can be high due to the large number of backer bars used in the machine.
Some anticurl backside coating formulations are disclosed in U.S. Pat. Nos. 5,069,993 and 5,021,309.
The anticurl backside coating layers illustrated herein, in embodiments, have excellent wear resistance, extended lifetimes, minimal charge buildup, and permit the elimination or minimization of photoconductive imaging member belt ACBC scratches.
Also included within the scope of the present disclosure are methods of imaging and printing with the photoresponsive or photoconductor devices illustrated herein. These methods generally involve the formation of an electrostatic latent image on the imaging member, followed by developing the image with a toner composition comprised, for example, of thermoplastic resin, colorant, such as pigment, charge additive, and surface additive, reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the disclosures of which are totally incorporated herein by reference, subsequently transferring the toner image to a suitable image receiving substrate, and permanently affixing the image thereto. In those environments wherein the device is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, the flexible photoconductor belts disclosed herein can be selected for the Xerox Corporation iGEN® machines that generate with some versions over 100 copies per minute. Processes of imaging, especially xerographic imaging and printing, including digital, and/or color printing, are thus encompassed by the present disclosure. The imaging members are in embodiments sensitive in the wavelength region of, for example, from about 400 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this disclosure are useful in color xerographic applications, particularly high-speed color copying and printing processes.